Osteomyelitis (ah-stee-o-my-uh-LYE-tis) is a bone infection that is usually caused by bacteria. It can involve any bone in the body, but it most commonly affects the long bones of the arms and legs.
Osteomyelitis is usually caused by infection with bacteria. Staphylococcus aureus (stah-fih-lo-KAH-kus ARE-ree-us), streptococcal (streptuh-KAH-kul) species of bacteria * , and Pseudomonas aeruginosa (su-doe-MO-nas air-ew-jih-NO-suh) are the major organisms associated with osteomyelitis. These bacterial intruders can travel from other parts of the body, such as the ear, throat, or intestines * , through the bloodstream and to a bone, where they can start an infection. Bones that have been weakened or damaged, such as through a recent injury, are more susceptible to bacterial invasion. When there is trauma to the bone, such as a puncture wound from stepping on a nail, bacteria can infect the bone directly. Rarely, fungi may cause osteomyelitis and then spread through the body. Tuberculosis (too-ber-kyoo-LO-sis), a contagious disease caused by another bacteria mycobacterium tuberculosis that typically affects the lungs, also can lead to bone infection, usually in the spine.
In children, osteomyelitis occurs most often in the long bones of the leg, such as the femur (FEE-mur) and tibia (TIH-be-uh). Adults tend to have the infection in the hipbones and vertebrae * , where it may occur following surgery on a bone or from an infection that has spread from the skin. People with diabetes * can have osteomyelitis in the foot bones from ulcerations or ulcers (open sores) on their feet.
Osteomyelitis that evolves rapidly is called acute osteomyelitis. If a bone infection persists because it is not treated or it does not respond to treatment, it is known as chronic osteomyelitis.
When the bone becomes infected in acute osteomyelitis, the skin that covers the bone usually becomes inflamed and swollen. The condition is diagnosed by a blood culture, by a biopsy (tissue sample), or by an x-ray or bone scan examination. If acute osteomyelitis is confirmed, antibiotic treatment begins immediately, often with an excellent chance of complete recovery.
In rare cases, tuberculosis, an infection of the lungs and sometimes other parts of the body, can spread to bones (especially the spine), causing a form of osteomyelitis. When tuberculosis is involved, drugs to combat tuberculosis are used to treat both conditions.
Chronic osteomyelitis occurs in about 2 in 10,000 people. Children have the acute form of the disease more often than adults. Children commonly have bloodstream spread of infection to long bones because actively growing bones are quite vascular * . Adults in whom the long bones are not growing and are less vascular have bloodstream spread to the bones of the spine. People who have diabetes, who have had a recent traumatic injury, or who use intravenous * drugs are at greatest risk for chronic infection.
Bone infections are not contagious. However, some types of bacteria that cause the infections that can progress to osteomyelitis are passed from person to person.
The first sign of acute infection may be a fever that begins suddenly. The area over the infected bone may become warm, red, and swollen, and the joints next to the bone may swell as well. As the infection progresses, it can cause pain in the affected bone and may limit the person's movement in that area. Individuals with acute osteomyelitis may feel irritable, nauseated, and generally very ill. They usually respond to intravenous antibiotic treatment; however, the medication is often irritating at the site of infusion.
Patients with chronic bone infection may experience drainage of pus * through the skin covering the affected bone. Due to local pain and drainage caused by the infection, individuals who have chronic osteomyelitis usually require surgical removal of dead, infected bone.
To help make the diagnosis, a doctor may order an x-ray of the suspect area to look for signs of bone inflammation * or damage, but changes in the bone may not show up for weeks after the infection begins. Magnetic resonance imaging * (MRI) or a computed tomography * (CT) scan may show changes that reflect osteomyelitis sooner than x-rays will. Radionuclide scans * may help pinpoint the location of the infection early in the course of the disease. Blood cultures * or, less commonly, a bone biopsy may identify the infectious agent.
Patients with osteomyelitis usually need to be hospitalized. They typically receive antibiotics for 4 to 6 weeks to combat the infection. At first, the medication is given intravenously, but patients may be switched to oral (by mouth) medicine as the treatment continues and their condition improves. In more serious and chronic cases, patients may need an operation to remove bits of bone that have died. To help new bone grow, surgeons may perform a bone graft, in which bone from another part of the body is placed in the spot where dead bone has been removed. Doctors may use packing material to fill in the open area temporarily.
Patients with osteomyelitis often need several weeks or months of treatment before the infection clears up. Acute cases may resolve after as little as one month of antibiotic therapy, but chronic cases can linger much longer.
In children, osteomyelitis can damage growing bones permanently, especially if it is not promptly and adequately treated. Infection may spread to the blood, overlying skin, or nearby joints. Bones may be weakened and break more easily. Movement of nearby joints or limbs may become limited. Occasionally, in chronic cases, severe infection or damage to the bone may result in the need to amputate, or remove, part or all of a limb.
See also Bacterial Infections • Diabetes • Staphylococcal Infections • Streptococcal Infections • Tuberculosis
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* bacteria (bak-TEER-ee-a) are single-celled microorganisms that typically reproduce by cell division. Some, but not all, types of bacteria can cause disease in humans.
* intestines are the muscular tubes that food passes through during digestion after it exits the stomach.
* vertebrae (VER-tuh-bray) are the bones that form a column surrounding the spinal cord; there are 39 vertebrae in the spine.
* diabetes (dye-uh-BEE-teez) is a condition in which the body's pancreas does not produce enough insulin or the body cannot use the insulin it makes effectively, resulting in increased levels of sugar in the blood.
* vascular refers to veins and arteries (the blood vessels).
* intravenous (in-tra-VEE-nus), or IV, means within or through a vein. For example, medications, fluid, or other substances can be given through a needle or soft tube inserted through the skin's surface directly into a vein.
* pus is a thick, creamy fluid, usually yellow or ivory in color, that forms at the site of an infection. Pus contains infection-fighting white cells and other substances.
* inflammation (in-fla-MAY-shun) is the body's reaction to irritation, infection, or injury that often involves swelling, pain, redness, and warmth.
* magnetic resonance imaging (or MRI) uses magnetic waves, instead of x-rays, to scan the body and produce detailed pictures of the body's structures.
* computed tomography (kom-PYOO-ted toe-MAH-gruh-fee), or CT, is a technique in which a machine takes many x-rays of the body to create a three-dimensional picture. Formerly known as computerized axial tomography (CAT).
* radionuclide scans (ray-dee-oNU-klide) are tests that begin by giving a patient a small amount of a radioactive substance. The radioactive substance shows up on a scan, producing a view of the structure or function of the part of the body being studied.
* cultures (KUL-churz) are tests in which a sample of fluid or tissue from the body is placed in a dish containing material that supports the growth of certain organisms. Typically, within days, the organisms will grow and can be identified.